1. Field of the Invention
The present invention relates to a hydraulic chair lift for arrangement in a vehicle, like a car or a van, which hydraulic chair lift includes a rod with attachment means on both ends for attachment with the floor and the roof zone of the vehicle; a piston arranged around the rod in a middle zone of the rod; a barrel enveloping the piston; and two heads arranged on each end of the barrel, which heads are provided with a channel for passage of the rod, wherein a rod gland is arranged in the head surrounding the channel.
2. Description of Related Art
Such chair lifts are mounted in vehicles to assist in lifting disabled people in and out the vehicle. A chair frame is mounted to the barrel and by feeding hydraulic oil on either side of the piston the chair frame can be brought up or let down. The vehicle chair or a separate chair is lifted and the chair frame is then rotated around the rod to bring the chair outside the vehicle, after which the lift is let down to bring the chair down on the street. Wheels can for example be mounted to the chair, such that it can be used as a wheel chair. To lift someone into the vehicle, the reverse process is performed.
Using a hydraulic cylinder as a chair lift for vehicles gives a large momentum on the hydraulic cylinder. As a result the rod will bent. The bending of the rod will give problems in the heads of the cylinder, which could cause leakage or heavy rotation.
Typically, a person skilled in the art would add additional sealings to the rod gland, to avoid leakage in such applications. The rod gland often has also another seal called a rod wiper which prevents contaminants from entering the cylinder when the extended rod retracts back into the cylinder.
However, with a chair lift according to the preamble, it is also necessary to rotate the chair around the rod. When additional sealings are added, the friction in the heads will increase, making it more difficult to rotate the chair around the rod by hand.